A conventional stator coil winder includes a needle shaft into which a wire is inserted and which is reciprocated in an axial direction to cause a needle attached to the end of the needle shaft to be inserted in the slot of a stator core. The needle shaft reciprocally rotates at a predetermined angle around the axial line of the stator core, and the wire is wound around at the neck of each pole. Two types of stator coil winders, a horizontal type and a longitudinal type, are currently in use. The type of winder is determined by the direction of axial movement of the needle shaft. Because these winders have similar compositions, only one, a horizontal winder, will be discussed herein.
FIG. 8 presents a cross sectional view showing the principal parts of a conventional horizontal type stator coil winder. In the horizontal winder, a timing belt 2 transmits the rotation of a drive motor 1 to a timing pulley 3. The motor 1 drives and rotates a rotary plate 5 via a rotary shaft 4 integral with the pulley 3. A crank pin 6 journalled to the rotary plate 5 at an eccentric position drives a slider 9 by means of a crank arm 7 and a linkage pin 8, thereby composing the crank mechanism.
A slider 9 slides on a guide shaft 11 in an oil-tight crank case 10 which contains oil. The slider 9 causes a pipe-like linkage shaft 12 linked with the slider 9 by a threaded connection to move in the same direction as the slider 9. A pipe-like needle shaft 13, which simultaneously moves in the axial direction thereof and rotates freely in the rotation direction, is linked with the linkage shaft 12, and a needle 13a is provided at one end thereof. The reciprocation of the needle shaft 13 causes the needle 13a to insert into the stator S.
The rotation of a rotary shaft 4 is transmitted to a conventional swing mechanism 16 which intermittently operates, via a timing pulley 14 and timing belt 15, thereby causing the needle shaft 13, which is spline-connected to a rotating drive gear 18, to be swung to an appointed angle by a fan-shaped gear 17 and a rotating drive gear 18. Stator core S winding is carried out with the wires W which are supplied through the linkage member 12, needle shaft 13 and needle 13a.
A tension device (not illustrated) consisting of, for example, a magnetic particle type electromagnetic clutch, provides wire tension before the wire is inserted into the linkage member 12, thereby preventing disorder of the wire when winding and maintaining a good winding accuracy to increase the occupancy ratio of coils.
These conventional stator coil winders have remarkably long wire routing lengths, such as 1.2 m, because the linkage shaft and needle shaft, into which a wire is inserted, penetrate through a long crank case which is internally provided with a crank mechanism and swing mechanism. Thus, in a case where the wire routing length is long and the position where wire tension will be produced is far from the needle, the wire swings in the linkage shaft and needle shaft producing unnecessary and unwanted tension. For example, in a case where the wire is fine, the tension necessary for good winding, which is given by the tension device, may be 10 kgf. A fine wire may be inadvertently severed if the tension which is generated due to swing of the wire exceeds 10 kgf. For this reason, to reduce wire breakage, the wire will be given an initial tension of 5 kgf, for example. Therefore, in a normal state in which no tension is generated due to swings, the wire tension decreases when winding, thereby decreasing the winding accuracy. This results in the required number of windings not being made on the stator. Furthermore, because the needle shaft is supported on only one side, i.e., at the base side, swing is generated at the tip of the needle on which force operates, thereby adversely influencing the stability of the windings. Furthermore, the wire supplying spools and buckets are located opposite the operator's side of the winder making wire replacement cumbersome.
In view of these problems, the present invention was developed, and it is therefore an object of the invention to increase, by reducing the fluctuations of tension due to swing, the winding accuracy to prevent the wire from being inadvertently severed and, simultaneously, to make wire replacement more efficient.